1. Field of the Invention
The present invention relates to a method of judging the lip turnover of a seal having a lip, such as an oil seal or G seal with a lip, in inserting the seal onto a shaft, and an apparatus for inserting such a seal.
2. Description of the Related Art
In seals with a lip, the point portion of the lip consisting of an elastic member, such as rubber, makes close contact with a shaft to form a seal portion and prevents leakage of oil and invasion of foreign matter, such as dust, with the seal portion. When such a seal with a lip is fitted on a shaft, the direction of the lip must be directed in a direction in which the seal is inserted onto the shaft.
However, there are cases where at the time of insertion the lip of the seal is turned over due to friction between it and the shaft and is directed in a direction opposite the insertion direction. If the lip is turned over in this way, a gap will be developed between the seal portion and the shaft and a situation such as leakage of oil and invasion of dust will take place.
For example, in Japan Utility Model No. 3007446 (Japan Utility Model Application No. HEI 6-10536), it has been proposed to provide a cutout in the outer circumferential edge to easily detect by an air leakage test whether or not the lip has been turned over.
The air leakage test, however, requires an air supply unit, piping for passing air from the air supply unit to a chuck hand for clamping a seal, and an expensive sensor for detecting air leakage. Furthermore, an exclusive chuck hand for leakage detection is required. Thus, providing large-scale equipment solely for the purpose of detecting the turnover of a seal is not only disadvantageous in costs, but it also takes time to detect air leakage. Furthermore, the production efficiency is reduced.